Help with calibration

newbie here, so any help is greatly appreciated…I’m just getting started with a Sainsmart genmitsu 3800 pro. I can do some basic carvings, but I’m trying to create a box using the easel box app, but the parts don’t fit together. They’re 2/8th of an inch too big to fit together. Also, the depth (z axis) is going almost 3/8th of an inch too deep (which ruins the box top groove cut out).

In candle, I have the X,Y & Z axis all set to 800, and I do not currently have digital calipers, but I took a board and marked off inch marks with a ruler. When I put my drill bit on 1 mark and jog the machine 1 inch to the right, it moves exactly 1 inch. Same for the Y and Z axis. So I thought my machine was well calibrated, but when it goes to carve something, obviously it’s well off.

Any thoughts on what I may be doing wrong? thanks!

  • Measure over the largest span each axis can travel, this will reduce the backlash component.
  • With the router powered OFF, pull/push by hand on the bit. How much does it deflect?
  • Pockets will be undersized, outside will be oversized, this offset need to be compensated by playing with bit diameter value (Trial and error, but 2/8" (1/4") is a lot)
  • I assume the bit follow the correct path, as in “Outside cut” on the outside and “Inside cut” for the pocket.

thank you for the reply! Yes, when I measure across the entire X & Y axis almost 12 inches across it still measures very accurately, less than 1/8th of an inch off perhaps.

As for the bit deflecting, it does move a bit if I really push on it, however when I cut that last box, I had the feed speed set very low, 6 or 9 in per minute which was almost as slow as it can go. It does deflect at higher speeds, but I thought the lower feed speed would help correct for that.

To help correct, do I set the diameter value bigger or smaller?


DOC will also effect deflection.
How deep per pass were you cutting?

easel has it set to 0.028 for the depth per pass.

what is “DOC”?

DOC is depth per pass.